To study the characteristics of erosive burning and gas flow in internal perforation of a tubular propellant, an interior ballistic model of a closed bomb was established considering the gas phase region inside the tube, gas phase region outside the tube and solid propellant region. The accuracy of the interior ballistic model and calculation method of the closed bomb was verified through comparing the numerical simulation results with the experimental data in the literature. On this basis, the effects of different length, internal diameter and loading density of propellant on the erosive burning of internal perforation were discussed respectively. Results show that for the tubular propellant with d=0.56 mm, l=50 mm, when 0.016≤ψ≤0.80(ψ is the burned percentage), the maximum pressure difference of internal and external perforation increases from 1.23 MPa to 2.00 MPa, the maximum gas velocity on the end face decreases from 430 m·s^-1 to 200 m·s^-1, the erosive burning coefficient on the end face decreases from 1.98 to 1.10, the erosive burning critical point of internal perforation moves from 7mm away from the symmetrical plane to 20 mm, the erosive burning area decreases by 65%. The ratio of burning surface to port area is an important factor affecting the erosive burning of internal perforation. The erosive burning does not occur when the ratio of burning surface to port area is less than 71.4. The erosive burning intensity becomes stronger with the increase of length and decrease of internal diameter, i.e. with the increase of the ratio of burning surface to port area, the erosive burning occurs evidently when the ratio of burning surface to port area is larger than 142.8. The maximum gas velocity on the end face and the erosive burning coefficient decrease slightly as the loading density increases, while the gas pressure difference of internal and external perforation increases obviously.